Abstract: A green part, a region of a refractory furnace or a hollow piece for producing a sintered refractory has the following mean mineral chemical composition in weight percent based of mineral oxides: 40%?Al2O3?94%, 0%?ZrO2?41%, 2%?SiO2?22%, 1%<Y2O3+V2O5+TiO2+Sb2O3+Yb2O3+Na2O. The sintered refractory products obtained from this green part give rise to a reduced bubbling effect.

Abstract: The invention relates to a hollow piece for producing a sintered refractory having the following mean mineral chemical composition in weight percent based of mineral oxides: 40%=Al2O3=94%, 0%=ZrO2=41%, 2%=SiO2=22%, 1%<Y2O3+V2O5+TiO2+Sb2O3+Yb2O3+Na2O.

Abstract: The invention relates to a hollow piece for producing a sintered refractory having the following mean mineral chemical composition in weight percent based of mineral oxides: 40%=Al2O3=94%, 0%=ZrO2=41%, 2%=SiO2=22%, 1%<Y2O3+V2O5+TiO2+Sb2O3+Yb2O3+Na2O.

Abstract: A heat exchanger for use in industries concerned with utilizing corrosive or abrasive fluids, either at low or high temperatures, is made of a monolithic body molded from refractory material and includes at least one channel for the fluid to be heated and at least one channel for the fluid to be cooled, these channels being integrally molded and in a mutual heat-exchange relationship.

Abstract: A refractory composition for use in the manufacture of pipes for casting steel, the composition consisting essentially of: (a) from 96 to 98% by weight of zirconia which is partially stabilized by CaO, MgO or Y.sub.2 O.sub.3, at least 90% of which has a particle size of between 0.1 and 10 .mu.m, and (b) from 2 to 4% by weight of an aluminous hydraulic binder, this composition having the following overall chemical analysis: 1.4 to 3.2% by weight of Al.sub.2 O.sub.3, 3.7 to 4.6% by weight of CaO, or 0.36 to 1.15% by weight of CaO plus 2.7 to 3.5% by weight of MgO, or 0.36 to 1.15% by weight of CaO plus 5.36 to 8.80% of Y.sub.2 O.sub.3, less than 1% by weight of SiO.sub.2 +Na.sub.2 O+Fe.sub.2 O.sub.3 +TiO.sub.2 taken together, and ZrO.sub.2 to make up to 100%.

Abstract: The invention refers to an unshaped refractory composition which can be used in the construction of glass furnace hearths and which comprises by weight:(a) 55 to 99% of particles of a fused cast refractory material, the fused cast refractory material including a vitreous phase and containing, as main constituents, ZrO.sub.2, Al.sub.2 O.sub.3, SiO.sub.2, and optionally Cr.sub.2 O.sub.3 ;(b) 0 to 5% of a hydraulic cement;(c) 1 to 15% of a filler consisting of very fine, substantially spherical particles of a metal oxide;(d) 0 to 25% of fine particles of a size less than 40 microns chosen from particles of ZrO.sub.2, Al.sub.2 O.sub.3, Cr.sub.2 O.sub.3, fused cast refractory products comprising by weight 75-85% ZrO.sub.2, 2-8% SiO.sub.2, 9-17% Al.sub.2 O.sub.3, 0.5-0.7% of other oxides, and mixtures thereof; and(e) 0.01 to 1% of a surface-active agent, the amount being with respect to the total weight of the constituents (a), (b), (c) and (d).